Interferon will be evaluated for its antineoplastic activity in the prevention and treatment of murine osteogenic sarcoma. The efficacy of interferon will be determined: (1) in tissue culture against a continuous line of osteogenic sarcoma cells derived from a 239Pu-induced osteogenic sarcoma in C57BL/6 mice, (2) in an in vivo model utilizing osteogenic sarcoma tumor cells implanted subcutaneously into syngeneic mice, and (3) in lung metastases established by intravenous inoculation of the continuous line of osteogenic sarcoma cells. If these initial experiments indicate efficacy in these experimental model systems, the capacity of interferon to prevent the induction of osteogenic sarcomas in mice exposed to 239Pu will be delineated and the treatment of established tumors will be attempted.